Interesting that two worked and two did not work. I am NOT in IT. In case it is helpful to others, the hardware version for my timer that did succeed in the firmware update is HT25-0000 (as found in the app when selecting the “Device Information”). I had originally purchased Orbit package 21004. The connection to my unit is not dropping out – but I have the WIFI (to Bluetooth) HUB located approximately 15 feet away from the timer with one external wall in between. New batteries were in the timer at the time of firmware update.